OBJECTIVE: To compare the emotional responses of mothers of late-preterm infants (34 0/7 to 36 6/7 weeks gestation) with those of mothers of full-term infants.DESIGN: A mixed method comparative study.SETTING: A southeastern tertiary academic medical center postpartum unit.PARTICIPANTS: Sixty mothers: 29 mothers of late-preterm infants and 31 mothers of full-term infants.METHODS: Measures of maternal emotional distress (four standardized measures of anxiety, postpartum depression, posttraumatic stress symptoms, and worry about infant health) and open-ended semistructured maternal interviews were conducted in the hospital following birth and by phone at one month postpartum.RESULTS: Mothers of late-preterm infants experienced significantly greater emotional distress immediately following delivery, and their distress levels continued to be higher at one month postpartum on each of the standardized measures. Mothers of late-preterm infants also discussed the altered trajectories in their birth and postpartum experiences and feeling unprepared for these unexpected events as a source of ongoing emotional distress.CONCLUSION: Mothers of late-preterm infants have greater emotional distress than mothers of term infants for at least one month after delivery. Our findings suggest that it may not be a single event that leads to different distress levels in mothers of late-preterm and full-term infants but rather the interaction of multiple alterations in the labor and delivery process and the poorer-than-expected infant health outcomes. In the future, researchers need to examine how and when mothers' emotional responses change over time and how their responses relate to parenting and infant health and development.